Field of the Invention
The present invention relates to an interchangeable lens apparatus having a function of correcting information its image capturing optical system detected by using a signal output from an image sensor and to a lens-interchangeable image capturing apparatus.
Description of the Related Art
Lens-interchangeable image capturing apparatuses includes ones each capable of detecting information on an image capturing optical system of a lens apparatus (interchangeable lens) by using a signal from its image sensor. Examples of those include a lens-interchangeable image capturing apparatus including an image sensor provided with multiple focus detection pixels and photoelectrically converting an object image to produce a captured image and being capable of detecting a focus state of the image capturing optical system by a phase difference detection method using signals from the focus detection pixels (the method is hereinafter referred to as “an imaging-surface phase difference detection method”).
In the imaging-surface phase difference detection method, a light flux received by the focus detection pixels producing focus detection signals (image signals) to be used for focus detection and a light flux received by image capturing pixels producing image capturing signals for producing a captured image or a captured video are mutually different. For this reason, influences of aberrations (e.g., spherical aberration, astigmatism and coma aberration) of the image capturing optical system on the focus detection signals and those on the image capturing signals are mutually different. The difference may cause a difference between an in-focus position calculated from the focus detection signals and a best in-focus position shown by the image capturing signals. Furthermore, depending on a set pupil distance of micro lenses each provided for each focus detection pixel in the image sensor, a size of each pixel and others, influence degrees of the aberrations on the focus detection signals are mutually different.
For such a difference in the influence degrees of the aberrations on the focus detection signals, Japanese Patent Laid-Open No. 2010-263255 discloses a method of storing data of chromatic aberration of magnification in a lens apparatus and converting the stored data, by an image capturing apparatus, into data that reflects number of pixels of its image sensor and a pixel pitch thereof to perform correction of the chromatic aberration of magnification. Japanese Patent Laid-Open No. 2010-263255 also discloses that the data on the chromatic aberration of magnification that vary depending on lens states (focal length, image capturing distance, aperture value and the like) are decimated for interpolation in order to decrease a storage amount of the lens apparatus. In this case, performing an interpolation calculation by the lens apparatus or the image capturing apparatus enables acquiring data on the chromatic aberration of magnification depending on various lens states.
Furthermore, Japanese Patent Laid-Open No. 2013-042424 discloses a method of storing, in a ROM, an expression including an image height as a parameter to calculate a degree of marginal light quantity reduction, sending information on the marginal light quantity reduction calculated at the respective image heights by using the expression to an image capturing apparatus and then causing the image capturing apparatus to correct the marginal light quantity reduction.
The data on the chromatic aberration of magnification and on the marginal light quantity reduction disclosed in Japanese Patent Laid-Open Nos. 2010-263255 and 2013-042424 are data uniquely depending on image capturing conditions such a focal length of an image capturing optical system and an image capturing distance. For this reason, even when mutually different image sensors are used, amounts of the correction for the chromatic aberration of magnification and the marginal light quantity reduction can be calculated from the data uniquely depending on the image capturing conditions.
However, the correction amount corresponding to a difference between the in-focus position acquired from the focus detection signals and the best in-focus position acquired from the image capturing signals is difficult to be calculated for the different image sensors. This fact requires the lens apparatus to have correction values for individual image capturing apparatuses (that is, for individual image sensors), which increases in storage amount required by a storage medium to store the correction values.